1. Field of the Invention
The present invention relates to a manipulator apparatus and, more particularly, to a manipulator apparatus having a wide range of applications and good maintainability.
2. Description of the Related Art
As is known, conventional manipulator apparatuses include (1) a specialized manipulator having a manipulator main body constituted by components designed for a certain operation, and (2) a "module type manipulator" having a manipulator main body constituted by a combination of a plurality of standardized joint modules or arm modules.
In the former apparatus (1), various problems are posed when the operation target is changed. For example, assume that a manipulator apparatus having a long arm module, which is designed for a large working area, is to be used in a small working area. In this case, during an operation of the apparatus, the long arm module must always kept not to come into contact with sur rounding obstacles. Furthermore, in order to support the long arm module, an output from a joint driving section is wasted. Therefore, the output cannot be efficiently converted into power required for an end effector (e.g. hand unit) attached to the distal end of the arm module.
In contrast to this, the latter apparatus (2) can not only contribute to a reduction in the cost of the apparatus itself, but also cope with a change of operation target. In addition, the apparatus can contribute to the facilitation of maintenance.
As modules incorporated in the above-described "module type manipulator", a rotation joint module (disclosed in Japanese Patent Application 62-282886) and a link type arm module (disclosed in Published Examined Japanese Patent Application No. 63-50155) are known. By coupling and combining a plurality of modules of these types through mounting portions, a manipulator main body capable of performing a desired operation is provided.
The following problems, however, are also posed in the module type manipulator apparatus described above. In order to cause a manipulator main body to perform some operation after it is assembled by combining a plurality of modules, specialized software for driving/controlling the manipulator main body must be created. In creation of the software, the degree-of-free-direction (i.e., the degree of freedom of mobility and combination) of each joint module and the connecting direction and the length of each arm module need to be known in advance. If, however, the number and degree-of-free directions of joint modules are changed or arm modules having different lengths are combined in different directions every time the operation contents are changed, it often takes unexpectedly long time to confirm the degree-of-free-direction of each joint module and the length and direction of each arm module in an assembly site. In addition, after the confirmation, a series of operations (e.g., program creation, debugging, and testing) for the development of specialized software must be performed from the beginning. Therefore, it takes much labor and time to cause the manipulator apparatus to start a desired operation.
In order to eliminate such inconveniences, the apparatus may include an identification signal generator for outputting a signal corresponding to the degree-of-free direction of each joint module so that the degree of free direction of each joint module can be detected on the basis of an output from the signal generator. In spite of such improvement, whenever the length or direction of an arm module is changed in accordance with a change in working range, the size of the arm module must be measured again. It is, therefore, apparent that customization of software is difficult to realize.
As described above, the conventional module type manipulator apparatus requires much labor and time to update (e.g. reprograming for customizing) and change a program for driving/controlling the manipulator in accordance with a change in working range, thus imposing a heavy load on an operator.